Expandable bone device

ABSTRACT

An expandable bone device including a unitary body extending along a longitudinal axis and including a deformable distal end portion having a collapsed orientation for placement adjacent a spinal structure, the deformable distal end portion including relatively wide, mutually contiguous support surfaces outlined by relatively narrow cutouts, the support surfaces being contiguous with the rest of the unitary body via relatively narrow deformable splines, the deformable distal end portion having an expanded orientation wherein the support surfaces are moved transversely outwards away from and generally parallel to the longitudinal axis, and an actuator coupled to the deformable distal end portion and operative to cause movement of the deformable distal end portion between the collapsed orientation and the expanded orientation.

FIELD OF THE INVENTION

The present invention relates generally to expandable bone devices, suchas but not limited to, devices for vertebral body reconstruction(vertebroplasty), such as for treatment of compression fractures of thethoracic and lumbar spine area, or for an expandable bone device fortransversely displacing structures associated with the spine, forexample.

BACKGROUND OF THE INVENTION

Various instruments and methods for the treatment of compression-typebone fractures and other osteoporotic and/or non-osteoporotic conditionshave been developed. In one method, a cavity may be formed in the boneto be treated, followed by the insertion of an inflatable balloon-likedevice into the bone cavity. Inflation of the balloon-like device causesa compaction of the cancellous bone and/or bone marrow against the innercortical wall of the bone, thereby resulting in enlargement of the bonecavity and/or reduction of the compression fracture. The balloon-likedevice is then deflated and removed from the bone cavity. Abiocompatible filling material, such as methylmethacrylate cement or asynthetic bone substitute, is sometimes delivered into the bone cavityand allowed to set to a hardened condition to provide internalstructural support to the bone.

An example of a balloon-expanding device is U.S. Pat. No. 6,127,597 toBeyar et al., which describes a bone fixture for insertion through thebore of a bone and into the intramedullary cavity. The bone fixtureincludes a diameter-expandable, metallic balloon tube having an exteriorcircumferential surface. The tube has a reduced first diameter forinsertion through the bore and into the intramedullary cavity and asecond expanded diameter, wherein when fluid is introduced into saidbone fixture it radially increases in diameter from the reduced firstdiameter to the second expanded diameter.

However, it has been found that expansion of the balloon-like device isnot readily controllable. Instead, when such balloon-like device isinflated, expansion occurs along a path of least resistance. As aresult, the direction of compaction of the cancellous bone and/orreduction of the compression fracture is not controllable, and expansionoccurs in multiple directions and along multiple axes.

Another device for treatment of the spine is described in U.S. Pat. No.6,676,665 to Foley et al. This device includes an elongate member havinga deformable distal end portion at least partially formed of a flexibleand preferably elastic material. The distal end portion has an initialconfiguration for placement adjacent a vertebral body and a deformedconfiguration defining at least one outwardly extending projection fordisplacement of at least a portion of the vertebral body. The elongatemember preferably comprises a rod member, a sleeve member and anactuator mechanism for imparting relative linear displacement betweenthe rod and sleeve members to effect outward deformation of the distalend portion of the sleeve member. In one embodiment, the instrumentationis used to compact cancellous bone to form a cavity within a vertebralbody. In another embodiment, the instrumentation is used to reduce acompression fracture. In yet another embodiment, the instrumentation isused to distract a disc space between adjacent vertebral bodies.

U.S. Pat. No. 6,554,833 to Levy et al. describes a device forstabilizing bone, which includes a tubular body having first and secondend regions defining a longitudinal axis therebetween. A plurality ofsplines extend from the first end region, the splines including firstends coupled to the first end region, and second ends disposed away fromthe first end region, the second ends being directable from a generallyaxial collapsed state to a substantially transverse expanded state. Aplurality of support arms are coupled to the splines, and an actuator iscoupled to the support arms, the actuator movable axially relative tothe elongate body for causing the support arms to direct the second endsof the splines from the collapsed state to the expanded state.Optionally, the device includes another set of splines extending fromthe second end region or located at an intermediate region of thetubular body.

SUMMARY OF THE INVENTION

The present invention seeks to provide an expandable bone device, as isdescribed in detail further hereinbelow. The expandable bone device ofthe invention may be described hereinbelow for use with the spine (e.g.,the pedicles or spine processes and the like), but it is emphasized thatthe invention is not limited to the spine, and may be used for any bone,such as but not limited to, calcaneous, distal radius, upper tibia,hands bones and bone epiphysis. The invention may be used in thetreatment of any bone disease, disorder or problem, such as but notlimited to, fractures, prevention of trauma or fractures due toosteoporosis, endocrine, metabolic or tumoral bone diseases, AVN andtrauma. The invention may be used as “scaffolding” to support bonestructures, such as for filling bone structures (e.g., with cement, bonegraft, bone substitutes or collagen and other materials), and may or maynot be left in the bone structure, depending on the procedure used.

There is thus provided in accordance with an embodiment of the presentinvention an expandable bone device including a unitary body extendingalong a longitudinal axis and including a deformable distal end portionhaving a collapsed orientation for placement adjacent a spinalstructure, the deformable distal end portion including relatively wide,mutually contiguous support surfaces outlined by relatively narrowcutouts, the support surfaces being contiguous with the rest of theunitary body via relatively narrow deformable splines, the deformabledistal end portion having an expanded orientation wherein the supportsurfaces are moved transversely outwards away from and generallyparallel to the longitudinal axis, and an actuator coupled to thedeformable distal end portion and operative to cause movement of thedeformable distal end portion between the collapsed orientation and theexpanded orientation.

The expandable bone device may include one or more of the followingfeatures. For example, the support surfaces may be arranged in one ormore pairs of support surfaces that expand transversely outwards inopposite directions symmetrically or non-symmetrically with respect tothe longitudinal axis. Some of the narrow cutouts may be generallyparallel to the longitudinal axis. Additionally or alternatively, someof the narrow cutouts may be angled at a non-zero angle with respect tothe longitudinal axis. The deformable splines may be generally equallyspaced or are spaced at different distances from one another along thelongitudinal axis.

The unitary body may be generally cylindrical in shape. Alternatively,the unitary body may include a generally flat polygonal shape foldedabout a fold axis generally transverse to the longitudinal axis.

A bridge element may connect between two of the unitary bodies. Thedeformable distal end portion may include at least one non-smoothsurface adapted to adhere to a spinal structure. The unitary body mayinclude a non-deformable endpiece distal to the deformable distal endportion.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a simplified pictorial illustration of an expandable bonedevice, constructed and operative in accordance with an embodiment ofthe present invention, in a collapsed orientation, and including anon-deformable endpiece distal to a deformable distal end portion;

FIG. 2 is a simplified pictorial illustration of an expandable bonedevice, constructed and operative in accordance with another embodimentof the present invention, in a collapsed orientation, and without thenon-deformable endpiece;

FIG. 3A is a simplified pictorial illustration of the expandable bonedevice of FIG. 1 in an expanded orientation;

FIG. 3B is a simplified pictorial illustration of the expandable bonedevice of FIG. 2 in an expanded orientation;

FIGS. 4A, 4B and 4C are simplified pictorial illustrations of theexpandable bone device of FIG. 1, introduced into a vertebral bodythrough a pedicle, respectively, in collapsed, semi-expanded and fullyexpanded orientations;

FIGS. 5A, 5B and 5C are simplified pictorial illustrations of anexpandable bone device, constructed and operative in accordance with yetanother embodiment of the present invention, respectively, in collapsed,semi-expanded and fully expanded orientations;

FIG. 6A is a simplified pictorial illustration of an expandable bonedevice, constructed and operative in accordance with still anotherembodiment of the present invention, in a collapsed orientation, andincluding a non-deformable endpiece distal to the deformable distal endportion;

FIG. 6B is a simplified pictorial illustration of an expandable bonedevice, constructed and operative in accordance with another embodimentof the present invention, in a collapsed orientation, and without thenon-deformable endpiece;

FIG. 7A is a simplified pictorial illustration of the expandable bonedevice of FIG. 6A in an expanded orientation;

FIG. 7B is a simplified pictorial illustration of the expandable bonedevice of FIG. 6B in an expanded orientation;

FIG. 8 is a simplified pictorial illustration of an expandable bonedevice, constructed and operative in accordance with still anotherembodiment of the present invention, in a collapsed orientation;

FIGS. 9A, 9B, 10A and 10B are simplified pictorial illustrations ofexpandable bone devices, constructed and operative in accordance withother embodiments of the present invention, wherein the devices expandto prismatic shapes, respectively shown in contracted (FIGS. 9A and 10A)and expanded (FIGS. 9B and 10B) orientations; and

FIGS. 11A, 11B and 11C are pictorial illustrations of the expandablebone device of FIG. 1 with different actuators that may move thedeformable distal end portion between collapsed and expandedorientations, in accordance with different embodiments of the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference is now made to FIG. 1, which illustrates an expandable bonedevice 10, constructed and operative in accordance with an embodiment ofthe present invention.

The expandable bone device 10 may include a unitary body 12 extendingalong a longitudinal axis 14. Device 10 may include a deformable distalend portion 16 having a collapsed orientation for placement adjacent aspinal structure. The deformable distal end portion 16 may includerelatively wide, mutually contiguous support surfaces 18 outlined byrelatively narrow cutouts 20. The support surfaces 18 are contiguouswith the rest of the unitary body 12 via relatively narrow deformablesplines 22.

In the illustrated, non-limiting embodiment of FIG. 1, unitary body 12may be generally cylindrical in shape (although any other shape is alsoin the scope of the invention) and may include a non-deformable endpiece24 distal to the deformable distal end portion 16. The non-deformableendpiece 24 may be a ring contiguous with the rest of the unitary body12. One or more of the support surfaces 18 may be non-smooth forenhancing adhesion to spinal structure. Additionally or alternatively,one or more of the support surfaces 18 may be coated with a materialthat enhances adhesion with bone, such as but not limited to,hydroxyapatite. The support surfaces in the illustrated embodiments arearcuate (following the contour of the cylindrical shape) but may be anyother shape and size as well.

The expandable bone device 10 may be constructed, without limitation, ofmedically safe metals (e.g., stainless steel, shape memory alloys, suchas NITINOL) or plastics, including resorbable materials and shape memorypolymers.

As seen in FIG. 1, some of the narrow cutouts 20 may be generallyparallel to the longitudinal axis 14. Additionally or alternatively,some of the narrow cutouts 20 may be angled at a non-zero angle withrespect to the longitudinal axis 14. The deformable splines 22 may begenerally equally spaced or are spaced at different distances from oneanother along the longitudinal axis 14.

FIG. 1 illustrates a version of the expandable bone device 10 includingthe endpiece 24. FIG. 2 illustrates another non-limiting version ofexpandable bone device 10, referred to as expandable bone device 10′,without the non-deformable endpiece 24. Both FIGS. 1 and 2 illustratethe expandable bone device in a collapsed orientation.

An actuator 26 may be coupled to the deformable distal end portion 16.The actuator 26 may effect movement of the deformable distal end portion16 between the collapsed orientation and the expanded orientation.Without limitation, the actuator 26 may be similar to the actuator (alsoreferred to as the elongate control member) shown and described withreference to the embodiment of FIGS. 12-15D in U.S. Pat. No. 6,554,833.For example, the actuator 26 may be a threaded rod that mates withinternal threads formed in the unitary body 12. Rotation of the threadedrod may advance the rod distally towards the deformable distal endportion 16, as indicated by arrow 23. The threaded rod wedges into thedeformable distal end portion 16 and causes the support surfaces to movetransversely outwards away from and generally parallel to thelongitudinal axis 14, as indicated by arrows 25, to an expandedorientation. FIG. 3A and FIG. 3B illustrate the expandable bone devices10 and 10′, respectively, in the expanded orientations.

It is emphasized that the invention is not limited to theabove-described actuator 26 and other ways of expanding the deformabledistal end portion 16 may be used to carry out the invention as well,such as but not limited to, mechanical (manual or motorized), pneumatic,hydraulic or any other expansion method.

As seen in FIGS. 3A and 3B, the support surfaces 18 may be arranged inone or more pairs that expand transversely outwards in oppositedirections symmetrically or non-symmetrically with respect to thelongitudinal axis 14. For symmetrical expansion, the lengths of thedeformable splines 22 may be equal. For non-symmetrical expansion, thelengths of the deformable splines 22 may be different, making possibleexpansion at different or variable angles relative to the longitudinalaxis 14. Additionally or alternatively, deformable distal end portion 16with its support surfaces 18 may be deformed into different non-straightshapes (e.g., a wedge shape, a concave shape, a convex shape, etc.) bymaking the length of the deformable splines 22 gradually higher fromtheir proximal end to their distal end or vice-versa.

Reference is now made to FIGS. 4A, 4B and 4C, which illustrate that theexpandable bone device 10 may be gradually expanded and contracted in acontrolled manner. FIG. 4A illustrates introducing into the expandablebone device 10 into a vertebral body 30 through a pedicle 32. This is awell known approach used in spinal surgery called the transpedicularapproach, commonly used for introducing pedicle screws and forperforming vertebroplasty with a balloon or a cannula, such as forfilling the spinal body with bone cement or other materials.

FIG. 4B illustrates the expandable bone device 10 in a semi-expandedorientation. FIG. 4C illustrates the expandable bone device 10 in afully expanded orientation. The expansion is reversible and can bereversed for removal by collapsing the device in situ with the actuator26 or other tool. The expanded state can be locked.

A bridge element 43 (FIG. 3B) may be used to connect two unitary bodies12 together. The bridge element 43 may be situated in the posterior areaof the vertebra while the expanded device 10 is inside the vertebralbody (anterior aspect of the vertebra). Any number of expandable bonedevices 10 (not just one) may be introduced into the vertebral body orother bone.

Reference is now made to FIGS. 5A, 5B and 5C, which illustrate anexpandable bone device 50, constructed and operative in accordance withyet another embodiment of the present invention, respectively, incollapsed, semi-expanded and fully expanded orientations. Whereas in theembodiments of FIGS. 1 and 2 there are three deformable splines 22 foreach support surface 18, in the embodiments of FIGS. 5A-5C there are twodeformable splines 52 for each support surface 18. Any number ofdeformable splines may be used in the present invention. In theembodiments of FIGS. 1 and 2, the proximal ends of the support surfaces18 are separated by a gap 49 from the rest of the unitary body 12. Inthe embodiments of FIGS. 5A-5C, there is no such gap.

Reference is now made to FIG. 6A is a simplified pictorial illustrationof an expandable bone device 60, constructed and operative in accordancewith still another embodiment of the present invention, in a collapsedorientation.

The expandable bone device 60 is similar to the expandable bone device10, with like elements being designated by like numerals. In expandablebone device 60, there are narrow cutouts 62 angled at a non-zero anglewith respect to the longitudinal axis 14. FIG. 6B illustrates anothernon-limiting version of expandable bone device 60, referred to asexpandable bone device 60′, without the non-deformable endpiece 24. BothFIGS. 6A and 6B illustrate the expandable bone device in a collapsedorientation. FIGS. 7A and 7B illustrate the expandable bone devices 60and 60′, respectively, in an expanded orientation.

Reference is now made to FIG. 8, which illustrates an expandable bonedevice 70, constructed and operative in accordance with still anotherembodiment of the present invention, in a collapsed orientation. Theexpandable bone device 70 may be constructed of a unitary body 72 thathas a generally flat polygonal shape (e.g., rectangular) folded about afold axis 74 generally transverse to a longitudinal axis 75. Device 70may include a deformable distal end portion 76 having a collapsedorientation for placement adjacent a spinal structure. The deformabledistal end portion 76 may include relatively wide, mutually contiguoussupport surfaces 78 outlined by relatively narrow cutouts 80. Thesupport surfaces 78 are contiguous with the rest of the unitary body 72via relatively narrow deformable splines 82. An actuator (not shown) maybe coupled to the deformable distal end portion 76 for moving thedeformable distal end portion 76 between the collapsed orientation andthe expanded orientation, as similarly described hereinabove.

Reference is now made to FIGS. 9A and 9B, and 10A and 10B, whichillustrate expandable bone devices 90 and 100, constructed and operativein accordance with other embodiments of the present invention. Theexpandable bone devices 90 and 100 may be constructed like stents, suchas but not limited to, braided stents (filaments or wires, wound orbraided into a particular configuration), or mesh stents (metal meshbent or formed into a particular shape), among others (e.g., struts orother shapes and kinds of connecting elements). As is typical withstents, the expandable bone devices 90 and 100 may have a deformableportion 92 (102, respectively) with a compressed (e.g., collapsed,deformed, deflated or contracted) orientation (FIGS. 9A and 10A,respectively) which may be expanded to an expanded orientation (FIGS. 9Band 10B, respectively). The expansion may be effected by springelasticity, balloon or mechanical expansion, or by the self-expansion ofa thermally or stress-induced return of a shape memory alloy (such as anickel-titanium alloy, e.g., NITINOL) to a pre-conditioned expandedconfiguration.

In accordance with non-limiting embodiments of the present invention,the devices 90 and 100 expand to prismatic shapes. For example, thedevice 90 may expand to a three-dimensional rectangular prismatic shape.The device 100 may expand to a three-dimensional trapezoidal shape.These are just two non-limiting examples, and the invention is notlimited to any particular shape.

In the collapsed state of FIGS. 9A and 10A, the device may be introducedthrough the pedicles, such as with a sheath or catheter, as is knownwith stents. The device may be useful, for example, for treatingfractures (wherein no large size reduction is required) or forpreventive treatment of weak non-fractured vertebras.

Reference is now made to FIGS. 11A, 11B and 11C, which illustrate theexpandable bone device 10 with different actuators (structures 114, 116and 118, respectively) that may be coupled to the deformable distal endportion 16 to cause movement of the deformable distal end portion 16between the collapsed orientation and the expanded orientation, inaccordance with embodiments of the present invention. It is noted that“coupled to” encompasses both mechanical direct and indirect linkage aswell as non-mechanical coupling, such as but not limited to, electrical,hydraulic and pneumatic, for example. The expandable bone device 10 maybe expanded by the actuator, and the actuator may be left in place toform support structure for the device 10. Alternatively, the expandablebone device 10 may be expanded to form a skeletal structure wherein theactuator is removed after expansion.

As another alternative, the structures 114, 116 and 118 may not be usedas actuators, but rather as support structures. That is, the expandablebone device 10 may be expanded with some other actuator (not shown here)and the structures 114, 116 and 118 may be introduced into the expandedbone device 10 to provide extra support in situ.

In accordance with one embodiment of the invention, each actuator (orsupport structure) includes an elongate strip 120 with one or more scorelines 122 about which the strip 120 can bend to take on different shapesand forms. For example, in FIG. 11A, the actuator (or support structure)has an arcuate expanded shape (e.g., oval spheroid shape). In FIG. 11B,the actuator (or support structure) has a polygonal shape (e.g., diamondshape). In FIG. 11C, the actuator (or support structure) has anotherpolygonal shape (e.g., trapezoidal shape). The actuator may have anycombination of these shapes or other shapes as well. The actuator (orsupport structure) may be made of the same or similar material as thatof expandable bone device 10 but with different hardness, stiffness orother mechanical properties, or with different dimensions (e.g.,thickness and wideness) and shape. The selection of different materialsand properties allows different degrees of stiffness for the supportingstructure and for the whole system that may be used for different bones,patient ages and body parameters that answer the needs for adequatefixation in each case. The actuators (or supporting structures) may besupplied in a stock of different pieces, so the practitioner can choosethe best one for the job. They can be locked in place in many differentways.

It is appreciated that various features of the invention which are, forclarity, described in the contexts of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

1. An expandable bone device comprising: a unitary body extending alonga longitudinal axis and including a deformable distal end portion havinga collapsed orientation for placement adjacent a bone structure, saiddeformable distal end portion comprising relatively wide, mutuallycontiguous support surfaces outlined by relatively narrow cutouts, saidsupport surfaces being contiguous with the rest of the unitary body viarelatively narrow deformable splines, said deformable distal end portionhaving an expanded orientation wherein said support surfaces are movedtransversely outwards away from and generally parallel to thelongitudinal axis, and wherein in the expanded orientation, distal endsof said support surfaces are disconnected and distanced from one anotherby an open gap; and an actuator coupled to said deformable distal endportion and operative to cause movement of said deformable distal endportion between the collapsed orientation and the expanded orientationand wherein in the expanded orientation said deformable splines aremisshapen as compared to the collapsed orientation.
 2. The expandablebone device according to claim 1, wherein said support surfaces arearranged in at least one pair of support surfaces that expandtransversely outwards in opposite directions with respect to thelongitudinal axis.
 3. The expandable bone device according to claim 2,wherein the at least one pair of support surfaces expand transverselyoutwards in opposite directions symmetrically with respect to thelongitudinal axis.
 4. The expandable bone device according to claim 2,wherein the at least one pair of support surfaces expand transverselyoutwards in opposite directions non-symmetrically with respect to thelongitudinal axis.
 5. The expandable bone device according to claim 1,wherein some of said narrow cutouts are generally parallel to thelongitudinal axis.
 6. The expandable bone device according to claim 1,wherein some of said narrow cutouts are angled at a non-zero angle withrespect to the longitudinal axis.
 7. The expandable bone deviceaccording to claim 1, wherein said deformable splines are generallyequally spaced from one another along the longitudinal axis.
 8. Theexpandable bone device according to claim 1, wherein at least some ofsaid deformable splines are spaced at different distances from oneanother along the longitudinal axis.
 9. The expandable bone deviceaccording to claim 1, wherein said unitary body comprises a generallyflat polygonal shape folded about a fold axis generally transverse tothe longitudinal axis.
 10. The expandable bone device according to claim1, further comprising a bridge element that connects between two of saidunitary bodies.
 11. The expandable bone device according to claim 1,wherein said deformable distal end portion comprises at least onenon-smooth surface adapted to adhere to a bone structure.
 12. Theexpandable bone device according to claim 1, wherein said unitary bodycomprises a non-deformable endpiece distal to said deformable distal endportion.
 13. The expandable bone device according to claim 1, whereinsaid actuator comprises an elongate strip with at least one score lineabout which the elongate strip is bendable.
 14. The expandable bonedevice according to claim 13, wherein said actuator has at least one ofan arcuate expanded shape and a polygonal shape.
 15. The expandable bonedevice according to claim 1, further comprising support structure thatsupports said deformable distal end portion, said support structurecomprising an elongate strip with at least one score line about whichthe elongate strip is bendable.